How we can prove boltzman constant?

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Discussion Overview

The discussion revolves around the Boltzmann constant, specifically how to prove or calculate its value and convert it between different units. Participants explore both the theoretical and practical aspects of understanding this physical constant.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks help to prove the Boltzmann constant and convert it to specific units (1.0356 x 10-22 Torr-liter/K).
  • Another participant suggests measuring the Ideal Gas Constant as a means to understand the Boltzmann constant, noting the relationship R = NAkB.
  • A participant expresses a desire to calculate the constant rather than measure it.
  • There is a clarification that the Boltzmann constant is a physical constant related to energy and temperature, not something to be calculated in a traditional sense.
  • One participant proposes starting from the ideal gas law (PV = NKT) to convert units but struggles to reach the expected result.
  • Another participant explains the conversion process from SI units to Torr-liters, providing a specific calculation.
  • There is a request for clarification on the SI value of the Boltzmann constant (1.3806504E-23 Pa*m3) and how it is derived.
  • One participant mentions that the value can be found through various online sources, indicating that it is widely accepted.
  • Another participant connects the Boltzmann constant to Boyle's Law as a potential source of understanding.

Areas of Agreement / Disagreement

Participants express differing views on whether the Boltzmann constant can be "proven" or simply measured. There is no consensus on the best method to approach the topic, and some confusion remains regarding the conversion and derivation of its value.

Contextual Notes

Participants reference various methods and sources for determining the Boltzmann constant, but there are unresolved questions about the expectations for calculating or proving its value. The discussion includes assumptions about unit conversions and the nature of physical constants.

Who May Find This Useful

This discussion may be of interest to those studying thermodynamics, statistical mechanics, or anyone looking to understand the Boltzmann constant and its applications in different unit systems.

phys111
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hello all

if some one here can help me to prove Boltzmann costant

from SI unit to reach that k= 1.0356 x 10-22 Torr-liter/K ?
 
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I don't know how you can 'prove' an experimental value. But I can tell you how to measure it.

Simplest way would just be to measure the Ideal Gas Constant, since that's just Boltzmann's constant in disguise ([tex]R = N_Ak_B[/tex]). Take a fixed amount of a relatively ideal gas (e.g. helium) at a fixed volume. Vary the temperature and measure the pressure. Plot p against T and the slope is N*kB.
 
thanks

but i need just to calculate it ?
 
I don't know what you expect to calculate it from? It's a physical constant, not a mathematical one. It's the fundamental relationship between energy and temperature. For different units of either, it wouldn't be needed at all.

The Kelvin scale of temperature is defined by the triple point of water, and so the Boltzmann constant in SI units is determined by that as well.
 
we can start from this relation

PV=N KT

& use convert from SI unit to This unit but i don't reach for the same result
 
Oh sorry, I thought you meant to somehow calculate it. You're saying you want to convert units.

Well if your pressure and volume is in SI units, pV = Pa*m3, so if you want it in Torr-liters you want to multiply by Pascal/Torr and liters/m3.
So (1/133.322368)*1000.

So 1.3806504E-23 (Pa*m3) =1.380 6504E-23*(1000/133.322368) (Torr*Liters) = 1.03513E-22 (Torr*Liters)
 
yes , right

but i don't understand
1.3806504E-23 (Pa*m3)
how you found it
if u can explane to me more
 
phys111 said:
yes , right

but i don't understand
1.3806504E-23 (Pa*m3)
how you found it
if u can explane to me more
That is the accepted value in SI units, which anybody can find using Google. The value is given by many sources:
It is not clear what the source of your confusion is. Do you want to know:
  • How is k determined experimentally?
  • Where can you look up the value of k?
  • Why are the units Pa*m3/K ?
  • Other?
 
thanks

we can find that from Boyle's Law

right
 

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